There has been heretofore known a projection display apparatus including an imager and a projection optics, the imager configured to modulate light emitted from a light source, the projection optics configured to project the light outputted from the imager onto a screen.
In order for the projection display apparatus to display a large image on the screen, a distance between the projection optics and the screen (hereinafter, projection distance) has to be long. In this respect, proposed is a projection display system which achieves reduction in the projection distance by using a reflecting mirror reflecting light outputted from an imager to a screen (for example, Patent Literature 1).
When the projection distance is made short, the projection display apparatus is placed near the screen. Thus, the projection display apparatus is more likely to enter user's field of view. Accordingly, the projection display apparatus has to project light in an oblique direction from above, below, or either side of the screen. For example, the projection display system described above, the imager and a projection optics are shifted from each other in the vertical direction in their positional relationship, and a concave mirror is used as the reflecting mirror. Thus, the reduction in the projection distance and the projection in the oblique direction are both achieved.
Note that, as a technique to simply achieve reduction in the projection distance, also proposed is a technique using a wide-angle lens as a lens constituting a projection optics (for example, Patent Literature 2).
In the technique using the reflecting mirror, the reflecting mirror is added to the conventional configuration. In the technique using the wide-angle lens as the lens constituting the projection optics, the size of the lens constituting the projection optics is larger than that of the conventional configuration. On the other hand, reduction in size and weight of a projection display system is desired to gain freedom in carrying and placing of the projection display system.